The invention relates to a barrier layer that is resistant to the transmission of moisture and oxygen. More particularly, the present invention relates to an article having such a barrier layer and methods of applying such a barrier layer to an article.
Different types of electronic devices such as, but not limited to, light emitting diodes (also referred hereinafter as xe2x80x9cLEDsxe2x80x9d), liquid crystal displays (also referred hereinafter as xe2x80x9cLCDsxe2x80x9d), photovoltaic articles, flat panel display devices, electrochromic articles, and organic electroluminescent devices (also referred hereinafter as xe2x80x9cOELDsxe2x80x9d) share a common architecture: each device includes at least one substrate and at least one xe2x80x9cactivexe2x80x9d layer.
Many of the materials that are used in the active layers of such devices are sensitive to environmental factors. Electrode materials in LEDs and OELDs are sensitive to air and moisture, as are the polymeric and organic compounds that are used in OELDs and the liquid crystal materials in LCDs. Exposure to the elementsxe2x80x94particularly oxygen and waterxe2x80x94may severely limit the lifetime of such devices.
Selection of a substantially impermeable substrate, such as glass, provides protection from environmental attack. Polymeric substrates that are used in flexible versions of such devices, however, do not provide adequate protection against oxygen and moisture. Consequently, at least one coating that is substantially impermeable to oxygen and water vapor must be applied to the polymeric substrate to achieve the desired level of protection.
Barrier materials have been applied to substrates using a variety of coating processes. Plasma enhanced chemical vapor deposition (PECVD), for example, has been used to deposit barrier materials. Typical PECVD processes, however, are relatively slow; i.e. the barrier material is deposited on the substrate at a rate of about 30 to 60 nm/min or less. In order to be commercially viable, the barrier coating must be applied to the substrate at a significantly higher deposition rate.
While barrier materials are needed to extend lifetimes of flexible display devices such as LCDs, LEDs, and OELDs to acceptable levels, the methods that are currently used to apply the needed barrier materials to substrates are too slow. Therefore, what is needed is a method of forming a barrier layer on a substrate at a high rate of deposition. What is also needed is a method of forming a barrier layer on a substrate to form an article having acceptable water vapor and oxygen transmission rates. What is further needed is an article having a barrier layer, the article having acceptable water vapor and oxygen transmission rates.
The present invention meets these and other needs by providing an article comprising a substrate having a barrier layer disposed on the surface of the substrate and methods of depositing such a barrier layer on the substrate, wherein the barrier layer is resistant to transmission of moisture and oxygen therethrough. The article may include additional layers, such as, but not limited to, an adhesion layer, abrasion resistant layers, radiation-absorbing layers, radiation-reflective layers, and conductive layers. Such articles Include, but are not limited to, light emitting diodes (LEDs), liquid crystal displays (LCDs), photovoltaic articles, electrochromic articles, organic integrated circuits, and organic electroluminescent devices (OELDs).
Accordingly, one aspect of the invention is to provide an article. The article comprises a substrate and at least one barrier layer disposed on at least one surface of the substrate, wherein the barrier layer comprises an inorganic material, and wherein the barrier layer is resistant to transmission of moisture and oxygen therethrough and has a water vapor transmission rate (WVTR) at 25xc2x0 C. and 100% relative humidity of less than about 2 g/m2-day and an oxygen transmission rate (OTR) at 25xc2x0 C. and 100% oxygen concentration of less than about 2 cc/m2-day.
A second aspect of the invention is to provide a barrier layer that is resistant to transmission of moisture and oxygen therethrough. The barrier layer comprises at least one of a metal oxide, a metal nitride, a metal carbide, and combinations thereof. Each of the metal nitride, the metal carbide, and the metal oxide contains at least one of silicon, aluminum, zinc, indium, tin, a transition metal, and combinations thereof. The barrier layer has a water vapor transmission rate (WVTR) at 25xc2x0 C. and 100% relative humidity of less than about 2 g/m2-day and an oxygen transmission rate (OTR) at 25xc2x0 C. and 100% oxygen concentration of less than about 2 cc/m2-day.
A third aspect of the invention is to provide an article. The article comprises a substrate and at least one barrier layer, the at least one barrier layer comprising at least one of a metal oxide, a metal nitride, a metal carbide, and combinations thereof, wherein each of the metal nitride, the metal carbide, and the metal oxide contains at least one of silicon, aluminum, zinc, indium, tin, a transition metal, and combinations thereof, and wherein the barrier layer is resistant to transmission of moisture and oxygen therethrough and has a water vapor transmission rate (WVTR) at 25xc2x0 C. and 100% relative humidity of less than about 2 g/m2-day and an oxygen transmission rate (OTR) at 25xc2x0 C. and 100% oxygen concentration of less than about 2 cc/m2-day.
A fourth aspect of the invention is to provide a method of forming a coated article. The coated article comprises a substrate and a barrier layer disposed thereon, wherein the barrier layer is resistant to transmission of moisture and oxygen therethrough and has a water vapor transmission rate (WVTR) at 25xc2x0 C. and 100% relative humidity of less than about 2 g/m2-day and an oxygen transmission rate (OTR) at 25xc2x0 C. and 100% oxygen concentration of less than about 2 cc/m2-day. The method comprises the steps of: providing a substrate; generating a thermal plasma, the thermal plasma having an electron temperature of less than about 1 eV; injecting at least one reagent into the thermal plasma; reacting the at least one reagent in the thermal plasma to form at least one deposition precursor; and depositing the at least one deposition precursor on the substrate at a rate of at least about 200 nm/min to form the barrier layer on the substrate.
A fifth aspect of the invention is to provide a method of forming a barrier layer on a substrate. The barrier layer is resistant to transmission of moisture and oxygen therethrough and has a water vapor transmission rate (WVTR) at 25xc2x0 C. and 100% relative humidity of less than about 2 g/m2-day and an oxygen transmission rate (OTR) at 25xc2x0 C. and 100% oxygen concentration of less than about 2 cc/m2-day, and comprises at least one of at least one of a metal oxide, a metal nitride, a metal carbide, and combinations thereof, wherein each of the metal nitride, the metal carbide, and the metal oxide contains at least one of silicon, aluminum, zinc, indium, tin, a transition metal, and combinations thereof. The method comprises the steps of: generating a thermal plasma, the thermal plasma having an electron temperature of less than about 1 eV; injecting a first reagent into the thermal plasma, the first reagent comprising at least one of silicon, aluminum, zinc, indium, tin, a transition metal, and combinations thereof; injecting a second reagent into the thermal plasma, the second reagent comprising at least one of oxygen, nitrogen, and ammonia; decomposing the first reagent and the second reagent in the thermal plasma to form a plurality of decomposition products; reacting the at least one reagent in the thermal plasma to form at least one deposition precursor; and depositing the at least one deposition precursor on the substrate at a rate of at least about 200 nm/min to form the barrier layer comprising at least one of a metal oxide, a metal nitride, a metal carbide, and combinations thereof on the substrate.
A sixth aspect of the invention is to provide a method of forming a coated article. The coated article comprises a substrate and a barrier layer disposed thereon. The barrier layer is resistant to transmission of moisture and oxygen therethrough and has a water vapor transmission rate (WVTR) at 25xc2x0 C. and 100% relative humidity of less than about 2 g/m2-day and an oxygen transmission rate (OTR) at 25xc2x0 C. and 100% oxygen concentration of less than about 2 cc/m2-day, and comprises at least one of a metal oxide, a metal nitride, a metal carbide, and combinations thereof, wherein each of the metal nitride, the metal carbide, and the metal oxide contains at least one of silicon, aluminum, zinc, indium, tin, a transition metal, and combinations thereof. The method comprises the steps of: providing a substrate; generating a thermal plasma, the thermal plasma having an electron temperature of less than about 1 eV; injecting a first reagent into the thermal plasma, the first reagent comprising at least one of silicon, aluminum, zinc, indium, tin, a transition metal, and combinations thereof; injecting a second reagent into the thermal plasma, the second reagent comprising at least one of oxygen, nitrogen, and ammonia; reacting the first reagent and the second reagent in the thermal plasma to form at least one deposition precursor; and depositing the at least one deposition precursor on the substrate at a rate of at least about 200 nm/min, thereby forming the barrier layer comprising at least one of a metal oxide, a metal nitride, a metal carbide, and combinations thereof on the substrate.
These and other aspects, advantages, and salient features of the present Invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.